Authors:

Human nature is perpetual. In most respects it is the same today as in the time of Caesar. So the principles of psychology are fixed and enduring

Dr. Robert C. Worstell, Claude C. Hopkins (2014). “Scientific Advertising - Masters of Marketing Secrets: From the First Great Copywriter”, p.25, Lulu.com
Human nature is perpetual. In most respects it is the same today as in the time of Caesar. So the principles of psychology are fixed and enduring